1. Technical Field
The present disclosure relates to apparatus and methods for providing illumination. More particularly, the present disclosure relates to apparatus and methods for providing oblique illumination for use, for example, in the inspection of manufactured substrates.
2. Description of the Background Art
Inspection processes are used at various steps during a semiconductor manufacturing process to promote higher yield. However, as the dimensions of semiconductor devices decrease, the detection of defects of decreasing size has become necessary to avoid unwanted manufacturing errors in the devices.
One way to improve the detection of such very small defects is to increase the sensitivity of an optical inspection system. The sensitivity of an optical inspection system may be increased, for example, by using oblique illumination, instead of normal illumination.